Conventional information storage devices typically include one or more heads for reading and writing data from and to a disk. For example, in an optical disk drive, the head will typically include a mirror and objective lens for reflecting and focusing a laser beam on to a surface of the disk. In magnetic recording applications, the head will typically include a transducer having a writer that may be of a longitudinal or perpendicular design, and a read element that may be inductive or magnetoresistive. The heads are typically positioned relative to concentric circular tracks of information on the disk by an actuator assembly to which the heads pertain. The angular position of the actuator assembly is typically controlled by a torque produced by a voice coil motor (VCM). A flex cable assembly will typically carry the signals from/to a printed circuit assembly (PCBA) to/from the heads as the heads write and read information recorded in concentric circular tracks on the disks.
FIG. 1 is an exploded top perspective view of a portion of a conventional disk drive (without any cover shown so that interior parts may be viewed). Now referring to FIG. 1, the flex cable assembly 100 typically includes a flex cable 102 that runs from the actuator to a flex bracket 104. The flex bracket typically includes a connector to electrically couple the flex cable to the PCBA. The flex bracket 104 is typically attached to a base 112 of the disk drive 110. The connector typically passes through the disk drive base 112 and therefore typically must be sealed with the disk drive base 112 to prevent contamination from entering the disk drive 110.
In the conventional disk drive 110 of FIG. 1, the flex bracket 104 is positioned relative to the disk drive base 112 by contact between a connector that protrudes from the underside of flex bracket 104 and a plurality of positioning pads 114 on the sides of an opening 116 through the disk drive base 112 (through which the connector passes). Registration of the flex bracket 104 on the positioning pads 114 ensures that the connector will have adequate alignment with a mating connector on the PCBA.
Posts 118 and 120 may be cast into the disk drive base 112. Although the posts 118 and 120 protrude into hole 106 and slot 108 of the flex bracket 104, respectively, the hole 106 and slot 108 have large enough dimensions so that entry of posts 118 and 120 into hole 106 and slot 108, respectively, does not interfere with the positioning of the flex bracket 104 by the positioning pads 114. The flex cable may include a flex stiffener at one or both ends to help control the exit angle θ of the flex cable 102 from the flex bracket 104 and/or the actuator assembly. However, positioning pads 114 serve to control the relative position of the connector of the flex bracket 104 with the PCBA better than they serve to control the exit angle θ and/or the position where the flex cable 102 exits from the flex bracket 104.
The flex cable is typically longer than the shortest length required to span the distance between the actuator assembly and the flex bracket, because it is not desired for the flex cable to constrain the angular range of motion of the actuator. The excess length in the flex cable forms a curve that allows the actuator assembly to be electrically coupled yet mechanically compliant to the applied torque from the VCM. Still, the flex cable exerts some biasing torque on the actuator, which must be overcome and compensated for by the VCM. To control the motion of the actuator assembly, it is desirable for the flex biasing torque to be small, known, and repeatable. However, excessive part-to-part variation in the position of the flex cable attachment points relative to the other disk drive components can cause excessive variation in the flex biasing torque that is experienced by the actuator. Presently millions of disk drives and other information storage devices are manufactured every year. Accordingly, there is need in the art for flex cable brackets that can more precisely position flex cables within disk drives, practically, in a high-volume manufacturing environment.